1. Field of the Invention
The present invention relates to a parallel moving device, and an actuator, a lens unit, and a camera that includes the parallel moving device.
2. Description of the Related Art
In a lens device provided with an imaging lens such as a variable magnification lens often employ a vibration-proofing device that prevents image blur caused by vibration due to hand jiggling, etc. In this type of vibration-proofing device, for example, the image blur is prevented by detecting vibration of a lens barrel housing an imaging lens, and by driving a correction lens on a plane parallel with a film so as not to cause the image blur based on the detected vibration. This type of vibration-proofing device is usually provided with a parallel moving mechanism that translates the correcting lens on a predetermined plane.
This type of parallel moving mechanism has, for example, a structure as follows. The parallel moving mechanism of a vibration-proofing device includes a fixed frame on which a correction lens is fixed, a first holding frame that slidably supports this fixed frame in a first direction perpendicular to an optical axis, and a second holding frame that slidably holds this first holding frame in a second direction substantially perpendicular to the optical axis and the first direction and that is fixed to the lens barrel.
And the correction lens is supported capable of a translational motion in an arbitrary direction in a plane parallel with a film with respect to the lens barrel by combining motions in the first and the second directions orthogonal to each other. Moreover, the vibration-proofing device provided with this type of parallel moving mechanism includes linear motors prepared exclusively for driving the correction lens in the first direction and the second direction, respectively, and the correction lens is moved in an arbitrary direction by combining driving amounts by these linear motors.
Also, in a lens device having an image blur preventing function by this type of vibration-proofing device, the parallel moving mechanism that supports the correction lens capable of parallel movement is provided with a combination of a guide unit that slidably guides the correction lens in a predetermined direction and a driving unit that drives the correction lens in that direction in each of the orthogonally crossing two directions (an X direction and a Y direction, for example) so as to move the correction lens in an arbitrary direction and to prevent the image blur (for example, Japanese Patent Application Laid-Open Publication No. H3-186823).
However, the conventional vibration-proofing device described in the above patent document has a problem that since the image blur is prevented by the parallel moving mechanism constructed by combining the guide unit arranged in the two directions orthogonal to each other and the driving units in those directions, a support mechanism of the fixed frame, and the holding frame can be complicated, for example. And if the support mechanism becomes complicated, weight of a movable part of the parallel moving mechanism increases, there by making high-speed and linear parallel movement difficult.
Furthermore, since sliding resistance is generated between the parallel moving mechanism and the guide unit in the conventional vibration-proofing device, controllability of the parallel moving mechanism is deteriorated. Moreover, an actuator using the guide units can move a movable part translationally in an arbitrary direction on a predetermined plane but the actuator can not move the movable part rotationally around the optical axis.
The guide unit or the support mechanism of the parallel moving mechanism in this structure requires some clearance to enable movement with small friction. Therefore, unintentional movement in a space corresponding to this clearance may occur, thereby causing a positioning error. In addition, if such clearance is provided, a load relating to driving is different between movement without contact between members and movement while sliding, thereby deteriorating control accuracy.